INTESTINAL ABSORPTION OF CALCIUM-47 AND STRONTIUM-85 IN LACTATING RATS

The absorption of calcium and strontium from the gastrointestinal tract was determined in lactating rats between the 14th and 16th day of lactation using radioactive isotopes of calcium (45Ca and47Ca) and strontium (85Sr) both in the in vivo and in the in vitro experiments. The absorbed dose of strontium and calcium (expressed as the sum of the radioactivity retained in the skeleton of the mother and litter and eliminated in urine) was determined in lactating animals after a two-day oral administration of radioactive isotopes. The absorbed radioactive dose in lactating animals was found to be 3 times as high for calcium and twice as high for strontium as in controls. The total amount of calcium and strontium absorbed from the intestinal tract of lactating animals was, however, about 6 and 4 times as high as in controls due to a two-fold increase in food consumption. The total passage of calcium and strontium from the mucosal to the serosal side of the everted duodenal sac in lactating animals was 2.8 and 3.4 times as high for strontium and calcium respectively as in controls. The active transport of calcium was also about twice normal in lactating animals. The authors discuss the possible morphological basis for these findings. © 1969 Springer-Verlag.